Compensating die holder

ABSTRACT

A single point compensating die holder for use with the bed of a press brake to provide vertical adjustment and compensating camber to the die holder. The vertical adjustment is provided by a single wedge member supported on the ends and transversely moved in the center by an adjustment means to effect positive or negative vertical crowning on the die holder having a coengaging inclined surface. Transverse movement of the wedge means is effected by the adjustment means engaging a connecting means connected to the wedge means and located in a recess below the wedge means.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to press brake metal forming machines and presses, and to improvements in die holders useful with such equipment. More particularly, the invention relates to single point compensating die holder.

[0003] 2. Background of the Prior Art

[0004] It is common practice in the operation of press brakes to use a die holder between the forming die and the associated bed of the press brake machine. It is also known to use a specially designed compensating die holder which uses movable wedges between the tool holder portion of the die holder assembly and the base portion of the die holder assembly. The purpose of the movable wedge or wedges which are located between the tool holder and the base section of the compensating die holder assembly is to provide a die holder unit which is capable of providing an evenly graduated crown wherein the center of the die holder is thicker or greater in height than the ends of the die holder. This crowning action of the die holder is desirable as it compensates for the deflection or bending away of the press brake ram and bed when subjected to metal forming pressures during normal operation. In the past this problem of press ram and bed deflection was compensated for by the use of thin layers of shim stock which were inserted between the die and the bed section of the press. It was necessary to place several layers of this shim stock, each cut to a different length, so as to create a gradually increasing elevation being thicker at the longitudinal center of the stack of shims and thinner at the ends. As each press brake machine has a different rate of deflection based on its tonnage capacity and overall length and each forming operation requires different tonnage's based on the length of the finished part, the shape desired in the finished part, the thickness of the material being formed and the tensile strength of the material being formed, it is easy to see that the shimming process is very difficult and time consuming, requiring a great deal of operator skill and experience.

[0005] In the past the long setup times required to shim the forming tools in order to produce good quality accurate parts was absorbed by producing a large number of parts once the press was properly set and shimmed. In the current manufacturing atmosphere the cost of warehousing large numbers of finished parts is no longer acceptable. Short production runs of high quality parts is now the rule for any successful manufacturer. In order to reduce the long setup times required by the use of shim stock crowning, several styles of compensating die holders have been developed.

[0006] Examples of such prior art teachings are found in the U.S. Pat. No. 2,199,864 to Wehr and U.S. Pat. No. 2,456,856 to Bath and U.S. Pat. No. 3,965,721 to Roch and U.S. Pat. No. 4,736,612 to Russell which teach the use of adjustable die holders to compensate for deflection in the bed or ram of the press brake in order to achieve straight bends and uniform bend angles in the articles being produced. Such prior developments generally have been successful and constitute material improvements over the more conventional, but time consuming use of shims beneath the die.

[0007] The principal difficulties encountered in using such prior compensating die holders are found in one or more of the following areas: the inability to adjust rapidly by means of a single adjusting point or the inability to reposition accurately to a predetermined precise crown or their inability to provide a visual means of confirming and/or recording their adjusted position.

[0008] Further examples of improvements in the prior art are found in U.S. Pat. No. 4,898,015 to Houston and U.S. Pat. No. 5,009,098 to van Merksteijn and U.S. Pat. No. 6,164,114 to Pelech, Jr. all of which teach adjustable die holders which incorporate the use of a single adjusting means to compensate for deflection in the bed or ram of the press brake in order to achieve straight bends and uniform bend angles in the articles being produced. However, further improvements are now necessary in order to keep up with increased quality and production demands in the field of sheet metal forming.

[0009] The principal difficulties encountered in using the above compensating die holders are found in one or more of the following areas. Some prior die holders are unable to withstand heavy bottom forming pressures because of voids created between the tool holder and the base caused by the adjusting wedge design, such as seen in U.S. Pat. No. 5,009,098 to van Merksteijn. Also, in the case of U.S. Pat. No. 4,898,015 to Houston and U.S. Pat. No. 6,164,114 to Pelech, Jr., problems exist pertaining to the inability to withstand rapid repeated adjustment because of the lack of lubrication at the drive mechanism or the inability to keep lubrication (if used) away from all surfaces of the wedge and its mating surfaces, which would allow the wedge to slip under pressure and thereby cause inaccurate and unpredictable bends. Some prior die holders are unable to provide an adjusting mechanism which can repeatedly sustain heavy forming tonnage's without damage to the adjusting means. Some prior die holders are unable to maintain consistent center-line alignment of the adjusting bolt and the operating nut means during adjustment which causes binding and difficult adjustment as well as premature failure of the adjusting means. Some prior die holders are unable to withstand normal stripping pressures without damage. Some have limitations regarding the diameter of the adjusting means thus reducing their tonnage capacity. Some are unable to operate in dirty environments without loss of accuracy. Some are unable to replace the connecting means between the adjusting means and the wedge means. Some are unable to position the adjusting means in an area away from and out of the way of the material being formed. Some are unable to be integrated with automated means by which the desired crown can be adjusted automatically by a press brake control system. For example, in both U.S. Pat. Nos. 4,898,015 and 6,164,114, the adjustment means moves vertically in response to adjustment of the crown, making it difficult to add an automated means to the adjustment means. Another substantial problem associated with the aforementioned patents is their inability to maintain the structural integrity of the wedge means used. Thinning the center portion of the wedge means with large diameter holes, grooves or pockets or the use of off-center adjustment means causes uneven bowing of the wedge means and therefore poor quality bends and crowning.

[0010] Yet another area of difficulty encountered in prior single point compensating systems is their inability to provide for negative crowning. This condition frequently occurs when multiple sets of short forming tools are used at the same time in a single press setup. When the forming tools located in the center of the press are used, normal deflection of the press bed and ram can be expected. However, when the forming tools located at the left or right side of the press are used, referred to as off-center loading, angular deflection of the press may occur. During this angular deflection condition of the press it may be necessary, in order to produce a good quality part, to reduce the height of the compensating die holder making it thinner in the center and thereby thicker at the ends. At this time only multiple point compensators similar to U.S. Pat. No. 4,736,612 to Russell can address this difficulty.

SUMMARY OF THE INVENTION

[0011] This invention provides an improved compensating die holder means which obviates the aforementioned problems of the prior art developments.

[0012] In brief, the present invention provides an improved single point compensating die holder in which a one piece wedge shaped die holder support, that is made to remain stationary at the ends of the die holder base while being transversely slidably movable in the center, is placed in an open channel of an underlying base; the die holder being positioned over the wedge means undersupporting the die holder with the wedge means being movable transversely of the base and die holder at the longitudinal center of the base and the die holder to selectively adjust the die support, thereby achieving a desired compensating camber to the undersupport of the die. In a preferred embodiment, adjustable movement of the wedge means is effected by threading engagement of a separate nut assembly keyed and mounted to the underside of the wedge means and located in an oil bath reservoir within the base block with rotatable adjusting bolt means which extend transversely through the base block beneath the die holder, with the wedge means moving along the axis of the associated adjusting bolt means and transversely across the channel of the base block at the longitudinal center of the base block while remaining in a fixed position at the ends of the base block. The radial position of the wedge adjusting bolt means may be effected by manual or power driven external means directly related to press operation. The desired crowning camber is accomplished by the longitudinal curvature generated in the wedge means when the longitudinal center of the wedge means is moved transversely by way of the adjusting bolt under the die holder section having a mating wedge angular face while the ends of the wedge means remains pivotably attached in a fixed position at the ends of the base block. Means for determining the exact position of the wedge member relative to the die holder and base block, and for visually indicating the position and the overall height of the crown or camber to the operator is made by way of a fixed mark incorporated in the exterior end of the adjusting bolt and a graduated indicator pin movable with the wedge member. The indicator such pin extends through one wall of the base block so as to be visually perceivable by the operator exteriorly of the base block and/or by way of a digital readout associated with an optional power drive unit externally mounted to the base block. The power drive unit is capable of rotating the adjusting bolt to a predetermined position controlled by the press controller or other related equipment and also capable of providing a numeric display of the wedge position which is readily understood by the operator.

[0013] An advantage of this invention is that it may provide a compensating die holder for a forming press having means to provide accurate and repeatable crowning from a single adjusting means capable of withstanding high forming pressures without damage.

[0014] Another important advantage of this invention is that it may provide an improved single point compensating die holder employing undersupporting wedge means capable of providing both positive and negative crowning configurations.

[0015] Another important advantage of this invention is that it may provide a single point compensating die holder assembly with undersupporting wedge means having a replaceable screw and nut drive.

[0016] Another important advantage of this invention is that it may provide a single point compensating die holder assembly where the centrally located nut drive assembly is designed to eliminate weakening of the wedge and thereby provide even bowing of the wedge as well as a convenient location for operator use.

[0017] Another important advantage of this invention is that it may provide a single point compensating die holder assembly with the means to use a heavy duty bolt and nut drive means in order to allow heavy load capacity while maintaining a low profile in order to preserve the maximum useable die space within the press.

[0018] Another important advantage of this invention is that it may provide a single point compensating die holder assembly wherein the adjusting bolt means extends through the base and is transversely secured by locking nut means against thrust bearings so as to insure the constant and precise transverse positioning of the aforementioned adjusting bolt means.

[0019] Another important advantage of this invention is that it may provide a single point compensating die holder assembly wherein the center-line of the adjusting bolt and nut remain on the same vertical plane at all times regardless of adjustment position.

[0020] Another important advantage of this invention is that it may provide a single point compensating die holder assembly having a nut drive assembly designed to operate in an oil bath so as to provide smooth and easy operation.

[0021] Another important advantage of this invention is that it may provide a single point compensating die holder assembly having a nut drive assembly designed to operate in an oil bath so as to provide extended operating life consisting of numerous rapid adjustments by manual or power driven means.

[0022] Another important advantage of this invention is that it may provide a single point compensating die holder assembly having an oil bath reservoir located under the wedge means and configured so as to insure that all mating wedge surfaces remain free of lubrication which can cause the wedge to slip when under load thereby causing the inaccurate and unpredictable forming of parts.

[0023] Another important advantage of this invention is that it may provide a single point compensating die holder assembly having a drive nut designed to automatically filter and circulate the lubrication oil through the engaging thread means of the drive screw and nut with each press stroke.

[0024] Another important advantage of this invention is that it may provide a single point compensating die holder assembly having a nut drive assembly designed to provide an accurate, centrally located, external visual reference for the position of the wedge means and thereby the degree of positive or negative crown produced.

[0025] Another important advantage of this invention is that it may provide a single point compensating die holder having a centrally located, external visual reference for the position of the wedge means which provides positive and accurate adjustment/measurement means which are unaffected by normal dirt or contamination.

[0026] Another important advantage of this invention is that it may provide a single point compensating die holder having both an indicator pin and a marked adjusting bolt designed to work in combination so as to provide the means for faster and more precise adjustment/measurement.

[0027] Another important advantage of this invention is that it may provide a single point compensating die holder having the means to withstand normal stripping pressures without sustaining damage.

[0028] Another important advantage of this invention is that it may provide a single point compensating die holder having the means to withstand normal stripping pressures without the need for additional holes and/or slots being provided in the wedge means, further degrading the integrity of the wedge means and therefore its ability to produce accurate bends.

[0029] Another important advantage of this invention is that it may provide a single point compensating die holder having the means to withstand and resist front to back or back to front loads encountered during normal operation.

[0030] Another important advantage of this invention is that it may provide a single point compensating die holder assembly which can accept an optional centrally located power driven actuator means designed to interact with and be controlled directly by a press control system.

[0031] Yet another important advantage of this invention is that it may provide a single point compensating die holder assembly with an optional power driven actuator means designed to interact with and be controlled by the press controller system while providing external visual reference of the wedge position at the longitudinal center of the compensator as well as a numeric positional reference at the press controller.

[0032] The above and further objects, features and advantages of the present invention will appear to those skilled in the art from the following description of a preferred embodiment, illustrated in the accompanying drawings and representing the best mode presently contemplated for enabling those skilled in the art to practice its teachings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURES

[0033]FIG. 1 is a perspective view of a single point compensating die holder assembly embodying the present invention;

[0034]FIG. 2 is an end elevation of a base block member employed in the assembly of FIG. 1;

[0035]FIGS. 3 and 4 are end elevations of a wedge member and die holder member, respectively, employed in the assembly of FIG. 1;

[0036]FIGS. 5 and 6 are end and top elevations, respectively, of the nut means employed to position the wedge means of FIG. 3;

[0037]FIG. 7 is an end and front elevation, respectively, of the oil wicking and filter means employed in cooperation with the nut means of FIGS. 5 and 6;

[0038]FIG. 8 is an enlarged top elevation of the indicator pin means employed in cooperation with the nut means of FIGS. 5 and 6;

[0039]FIG. 9 is an enlarged end elevation, with hidden lines, showing the assembly of FIG. 1 with the cooperating adjusting nut means assembly;

[0040]FIGS. 10 and 11 are end and foreshortened top elevations, respectively, of the single point compensating die holder assembly shown in FIG. 1, with the die and die holder removed, to illustrate the assembled adjustable wedge means;

[0041]FIG. 12 is a reduced scale of the top elevation as seen in FIGS. 10 and 11, showing the wedge, nut and indicating pin in a neutral operating, or zero crown position;

[0042]FIGS. 13, 14 and 15 are cross-sections of the assembly shown in FIG. 1 and sectioned transversely through the indicating pin, showing the cooperating nut, wedge and indicator pin means adjusted in the negative, neutral and positive crown positions, respectively;

[0043]FIG. 16 is a reduced front elevation of a typical press brake machine, showing typical center load deflection;

[0044]FIG. 17 is a reduced scale of the top elevation as seen in FIG. 10 and 11, showing the cooperating wedge, nut and indicating pin in a positive operating, or positive crown position;

[0045]FIG. 18 is a reduced front elevation of a typical press brake machine, showing typical off-center load deflection;

[0046]FIG. 19 is a reduced scale of the top elevation as seen in FIGS. 10 and 11, showing the cooperating wedge, nut and indicating pin in a negative operating, or negative crown position;

[0047]FIGS. 20 and 21 are foreshortened top and front elevations, respectively, of the center portion of the single point compensating die holder showing the optional addition of a power drive unit used to operate in cooperation with the adjusting screw and nut assembly, to provide an automatic interface and cooperation of the press brake and the single point compensating die holder.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0048] With reference now to FIGS. 1-8 of the drawings in particular, a base block 10 is shown (see FIG. 2) for use with the bed of a press brake including an elongated rigid metal body, having a generally U-shaped cross-section provided with an elongated rectangular cross sectioned channel 16 opening inwardly of the top face of the base block 10 and extending the full length of the base block. With respect to the base block, it may extend the full length of the press bed or be made in short sections to provide independent crown and height adjustments for multiple matched height tooling requirements. The base block 10 as shown is formed with two upwardly extending parallel arm portions 17 and 18 which laterally define the channel 16. Located in the longitudinal center of the base block 10 is a clearance hole 21, provided to accept the adjusting bolt 75 (seen in FIG. 9). The clearance hole 21 extends transversely through the base block 10, adjusting nut 30 and the rectangular shaped recess 22 provided in the base block. Pocket 22 accepts the adjusting nut 30 and acts as an oil lubrication reservoir. An additional clearance hole 23 having a smaller diameter is provided transversally through the front face 24 of the base block 10 and into the recess 22. This smaller diameter hole 23 is used to accept an indicator pin 25. On the bottom face of the base block 10 is a longitudinally extending groove 19 which accommodates an insert anchor tongue 20 in the illustrated case or alternatively such tongue 20 may be formed integrally with the base block 10. Tongue 20 is representative of only one of several configurations used by press brake manufacturers to secure die holders and/or dies to the bed of the press brake. It should be understood that the purpose of the tongue 20 is to hold the base block 10 from displacement both longitudinally and transversely of the press bed in operation. Other configurations which may be used for the mounting of the base block 10 to the press brake bed have no effect on the operation or the usefulness of this invention.

[0049] Mounted within the channel 16 and engaging the bottom wall 12 thereof is the wedge means 40 (see FIG. 3) comprising a single wedge member having the same overall length as the base block 10 and a width dimension less than the width of the channel 16. For example, if the channel is in the order of 3⅜ inches in width, the wedge member will be in the order of 2⅝ inches wide. This difference in dimension permits movement of the wedge transversely across the channel 16, as will be described in greater particular detail hereinafter. As shown, the wedge member 40 has an inclined upper wall 41 sloping transversely of the wedge body at a desired angle, for example about 10° to the horizontal. On the bottom face of the wedge 40 is a full length longitudinally extending keyway 42 which accommodates an insert key 45 integrally formed with the nut 30. Threaded mounting holes 43 are provided to allow attachment of the nut 30 to the bottom face of the wedge 40.

[0050] In the illustrated case (see FIG. 4) the die holder 50 constitutes an elongated metal body coextensive with the length of the base block 10 and having a width equal to the width of the base block. Vertical walls 51 and 52 are provided to allow a close supportive slip fit between the upwardly extending arm portions 17 and 18 of the channel 16 in the base block 10 so that the die support may slide vertically within the channel, closely guided by and between arms 17 and 18 of the base block. As shown, the lower face 54 of the die holder is sloped to match the upper face 41 of the wedge member, it will be appreciated that lateral movement of the wedge member 40 across the channel 16 beneath the sloping surface 54 of the die holder 50 will affect vertical movement of the latter within and between the parallel upright arms 17 and 18 of the base block.

[0051] As further illustrated in FIGS. 1 and 4 in particular, the die holder 50 is provided with flanged lip portions 55 and 56 along both longitudinal sides thereof. These flanges provide a surface for precise measurement of crown height by means of a feeler gauge between the undersurface of the lips 55 and 56 and the upper ends 26 and 27 of the base block arms. These flanges also provide some degree of protection from outside contamination which would otherwise find easy entry into the assembly. The upper wall 57 of the die holder is suitably channeled as shown at 58 to accept a tongue 121 of an overlying forming die 120 in assembly, as best illustrated in FIG. 1 of the drawings. With insertion of the tongue 121 into the channel opening 58 of the die holder, the die 120 is held in a fixed position on the die holder in the usual manner, such as by a series of set screws (see FIGS. 1 and 4) which travel in threaded openings 59 extending laterally through the upper sides of the die holder to invade the channel opening 58, and engage the die tongue 121 in a known manner.

[0052] Upward movement of the die holder 50 (whether caused by intentionally desired crowning or by the normal occurrence of stripping pressures which are common with the use of some forming tools), within the channel 16 of the base block is limited by a series of shoulder screws or bolts 85 (see FIG. 9), threadably attached to the base block 10 at the upper ends 26 and 27 of the base block arms at multiple spaced locations along the length thereof. Counter-bored holes 86 (see FIGS. 1 and 9) along opposite sides of the die holder provide stop shoulders 87, limiting the vertical movement of the die holder.

[0053] From the foregoing it will be appreciated that the described structure provides an assembly of the base block 10, wedge means 40, die holder 50 and forming die 120 in which the die holder 50 moves vertically within the confines of the base block's channel opening 16 in response to movement of the wedge means. In order to insure smooth, accurate movement of the die holder within the base block channel, the side walls of the die holder closely fit with the interior side walls of the channel opening 16 while the sloping underface 54 of the die holder and the upper face 41 of the wedge means are of identical angular disposition and interengage.

[0054] To actuate the wedge means 40 as heretofore described, a single adjusting means 75 is provided and extends transversely through the base block 10, the oil reservoir recess 22 (see FIGS. 2, 9 and 11) to the connecting means 30. The connecting means is preferably a nut 30 which is located and held securely in place to the bottom face of the wedge means 40 by the interengagement of the integral close fitting nut key 45 into the longitudinal wedge groove or keyway 42, as well as being threadably attached thereto by an adjusting bolt means 75 (although a hydraulic actuator or other adjustment means may be used). The oil reservoir recess 22 has longitudinal vertical walls 28 and 29 with a width dimension greater than the nut 30 so as to permit unobstructed transverse movement of the nut 30 within the oil reservoir as well as unobstructed transverse movement of the wedge 40 across the channel 16. The bottom face 39 of the oil reservoir recess 22 provides minimal clearance between the bottom nut face 31 so as to permit uninterrupted contact of the bottom face 44 of the wedge 40 with the bottom face 12 of the channel 16.

[0055] The nut 30 ( see FIGS. 5 and 6), has a full length longitudinal groove 32 in the bottom face 31 so as to permit insertion of a standard oil wicking material 38 as seen in FIG. 7. The groove 32 has a top face 33 which is made to invade the transversely positioned threaded bore 34 formed through the nut 30, providing an open window 35 directly into the threaded bore 34 so as to insure that oil wicking material 38 is in direct compressive contact with the actuating bolt means 75 and the bottom face 39 of the oil reservoir 22. The oil wicking material 38 is also in compressive contact with the vertical side walls of the nut groove 32 as well as the top face 33 of the nut groove. From the foregoing it will be appreciated that the described structure provides an assembly whereby the oil wicking material 38 provides several desirable functions, such as filtering the oil delivered to the actuating bolt means 75 through the open window 35, providing constant oil-wetted contact with the bolt means 75 and providing a positive pumping action of the lubricating oil into the threaded bore 34 formed through the nut 30. The positive pumping action is a natural result of whatever compressive action, caused by downward forces applied from the action of the press brake, which reduces the clearance between the bottom face 31 of the nut 30 and the bottom face 39 of the oil reservoir 22. Such reduction in the clearance will cause further compression of the engorged oil wicking material 38 thereby displacing a portion of the oil retained in the wicking material to be forced into the open window 35 of the nut 30. This process will be repeated with each stroke of the press brake thereby insuring the constant and predictable recirculation of filtered lubrication within the closed system to the movable bearing surfaces formed by the engagement of the bolt means 75 and the threaded bore 34 within the nut 30. A further feature of the nut 30 is the threaded bore 36 which is provided to receive a mating thread 61 from the indicator pin 25 which is provided to translate the exact position of the nut and wedge assembly through the front face 24 of the base block 10 after assembly. The nut 30 is provided with extra material on it's front face 37 so as to allow final machining of the surface 39 of the nut 30 after final assembly so as to insure exact positioning of the zero crown reference face 60 located on the indicator pin 25, as will be described in greater detail hereinafter. The nut 30 is preferably removable from the wedge means and is provided with multiple mounting holes 46 and counter bores 47 which are made so as to align with the mating threaded bores 43 of the wedge 40 wherein standard threaded fasteners are employed to provide secure attachment as an assembly. Another feature of the separate keyed nut 30 attachment to the wedge is realized by the low impact of the threaded fasteners on the overall rigidity of the wedge member, which will also be described in greater detail hereinafter.

[0056] As further illustrated in FIG. 8 the indicating pin means 25 has a generally cylindrical body 63 formed with a threaded end portion 61 of a reduced diameter which forms a shoulder wall 62 which is made to tightly abut with surface 39 of the nut 30 in assembly. This tight abutment is achieved by the interaction of the threaded section 61 of the indicator pin 25 and the threaded bore 36 of the nut 30 in a known manner by rotating forces that are applied to the indicator pin 25 at the screw driver slot 63 during assembly. The outer end of the indicator pin means is formed with scale means shown herein as including a plurality of alternate exterior lands 64 having an outside diameter similar to the diameter of the indicator pin body 63 and grooves 65 having a lesser diameter and opposing parallel walls 66. The outer most end of the indicator pin has an additional scale means with a further reduced outside diameter also formed by a plurality of lands 67 and yet further reduced grooves 68 having a lesser diameter and opposing parallel walls 69. By way of example, each land and groove may measure 0.055″ axially of the body 63. This measurement is in accordance with the wedge travel effectuated by one rotation of the through bolt means 75. In order to accurately reflect movement of the wedge means 40 and the associated nut means 30 attached thereto at the longitudinal center of the single point compensating die holder assembly, the indicator pin means 25 extends through a smooth walled bore opening 23 formed transversely through the front side of the base block 10 between the inside wall 28 of the oil reservoir 22 and the outer most front face 24 of the base block. When the single point compensating die holder is adjusted to the neutral, or zero crown position, the indicator pin surface 60, which is the dividing point between the large diameter scale and the smaller diameter scale, will be in smooth alignment with the front face 24 of the base block 10. The relationship of the indicating pin 25 and compensating die holder crown will be described in greater detail hereinafter.

[0057] As shown in FIGS. 9 and 11, the through adjusting bolt means 75 is comprised of a standard exteriorly threaded bolt having a standard hexagonal head 70 in which an indicating groove 71 is cut into the head so as to provide additional measurement means relating to the movement of the wedge assembly. The opposite end of the adjusting bolt is fitted with a castle nut and pin means 72. The adjusting bolt head 70 and the castle nut and pin means 72 reside outwardly of the side walls of the base block and are disposed over intervening thrust washers 73. With this arrangement rotation of the bolt means 75 serves to threadably advance or retract the longitudinal center of the wedge assembly across the bottom of the channel opening 16 in the base block. In the particular preferred embodiment illustrated, the threaded engagement of the through bolt with the wedge assembly is such that one full turn of the adjusting bolt effectuates a 0.010″ rise or fall of the die holder and a 0.055″ travel of the wedge assembly; the slope of the wedge being 10° to the horizontal. While such figures illustrate a typical arrangement, they are by no means limitive of the invention in that any desired selection of wedge slope and through adjusting bolt thread arrangement may be selected as desired. The aforementioned measuring groove 71 formed into the hexagonal head 70 of the adjusting bolt 75 is located generally defining one flat or side of the six sided bolt head. The groove as shown in FIG. 1 of the preferred embodiment is made to fade out as it extends toward the center of the bolt head so as to clearly define only one of the six flats which make up the adjusting bolt head. The purpose of the indicating groove 71 is to provide the means for a finer and more easily recognizable and repeatable adjustment by the press operator of the die holder crown which is accomplished by way of the movement of the wedge assembly which is dictated by the rotational movement and position of the adjusting bolt means 75.

[0058] It will be further appreciated that the relationship of the rotational movement of the adjusting bolt 75 and the position thereof as indicated by the adjusting bolt indicating groove means 71, when taken in consideration with the position of the indicating pin means 25, as is clearly displayed by the scale means thereof provided with the indicating pin and referenced by the position of the scale means as it relates with the front face 24 of the base block 10, will provide the press operator with easily repeatable accurate positioning of the wedge assembly and the subsequent die holder crown. For example, as shown in FIG. 11 the adjusting bolt 75 is in a position where the indicating groove 71 is clearly in the top most rotational position (the 12:00 o'clock position), and the indicating pin is shown having it's neutral crown face 60 in smooth alignment with the front face 24 of the base block 10. In consideration of both of the aforementioned indicating means, the die holder should be in a zero crown condition. If however, the adjusting bolt where shown in the same position but the indicating pin means was shown extending outwardly of the face 24 so as to align with the second edge of the pin, exposing one land 64 of the pin 25, there should then be a 0.010″ positive crown as one full rotation of the bolt 75 in the preferred embodiment will produce a 0.010″ rise of the die holder as well as advancing the indicating pin 0.055″ to the next measuring edge of the aforementioned pin. It also stands that if the pin where further advanced to the next edge, thereby exposing the first groove 65 of the indicating pin 25, the crown produced should be 0.020″. In FIG. 9 the adjusting bolt 75 is shown in a position where the indicating groove 71 is shown on the left side, or the 9:00 o'clock position. As the preferred embodiment employs a standard right handed thread arrangement and as the indicating pin 25 is clearly shown with the neutral crown face 60 extending outwardly of the front face 24 of the base block, it is clear that the adjusting bolt was rotated in a clockwise rotational direction to a position equal to ¾ of one full rotation (9:00 o'clock) thereby producing a crown equal to 0.0075″. It also stands that if the pin where further advanced exposing the entire first measuring land 64, but not yet exposing the entire first groove 65, the crown produced should be equal to one complete land (0.010″) plus ¾ turn (0.0075″) of the adjusting bolt which is equal to a total produced crown of 0.0175″. As one full turn of the adjusting bolt 75 will produce a positive or negative crown equal to 0.010″, it stands that each ¼ rotational turning adjustment of the bolt 75 will produce additional positive or negative crowning equal to 0.0025″ and each ⅛ rotational adjustment of the bolt 75 will produce additional positive or negative crowning equal to 0.00125″. This degree of accuracy is in most cases more than is required for normal press brake crowning adjustments. If however, even greater accuracy should be required, a simple graduated measurement means providing finer graduated reference markings could be provided as a stationary addition to the face of the base block encircling the rotatable adjusting bolt means and thereby providing even greater adjustment accuracy. It should be obvious from the above examples that both positive and negative crowning as well as accurate measurement of both positive and negative crowning will be possible with the above arrangement. It should also be obvious from the above examples that the combination of the indicating adjusting bolt means 75 along with the indicating pin means 25 will provide the press operator with a dependable, easily readable, recordable and repeatable measuring system for producing both positive and negative die holder crowns. It should further be obvious that the grooved indicator means 71 provided as an integral part of the adjusting bolt means 75 is capable of providing the press operator with an extremely accurate method of providing and determining fine adjustments made to the crowning system.

[0059] In FIG. 9 of the drawings a wave-like solid line 89 is shown extending transversely from a point equal to the bottom edge defined by the termination of the adjusting bolt clearance hole 21 which is bored through the front of the base block and entering the oil reservoir 22 to the bottom edge, defined by the continuation of the adjusting bolt clearance hole 21 exiting the oil reservoir 22, and continuing through the back of the base block. This wave-like solid line 89 is meant to depict the lubricating oil level which is found within the oil reservoir 22. In FIG. 1 a typical oil fill hole 76 is shown. It should be understood that this oil fill hole is located in such a manner that the bottom of the oil fill hole is at the same level as the bottom of the adjusting bolt clearance hole 21 noted above so as to provide a means of both filling the oil reservoir while also providing a method of determining that the oil has been filled to the proper level. This is accomplished by filling the oil reservoir 22 through the fill hole 76, which is positioned so as to invade the oil reservoir 22, until such time as the oil begins to leak back out through the fill hole 76. The oil fill hole 76 may also be provided with a typically known pipe thread means which will allow for the insertion of a standard pipe plug into the front face of the base block preventing the leakage of the lubricating oil after filling is completed. The oil fill hole 76, which is only shown in FIG. 1 for the sake of clarity, could be located in the rear of the compensating die holder if required by the addition of a power drive unit as will be described in greater detail hereinafter.

[0060] The benefits of oil lubrication are well known, and with this invention of a single point compensating die holder, where constant readjustment is expected and relatively heavy loads are anticipated during adjustment based on the overall weight of the die holder and the forming die members which will be installed into the compensating die holder, as well as the fact that the aforementioned weight of die holder and the forming tools attached to the die holder are to be raised or lowered by the interengagement of a single adjusting bolt and nut means as has been previously explained, the advantages of an oil lubrication system with regard to extended operating life and ease of operation are particularly obvious. In this invention however, there are additional factors which make this arrangement of the adjustment drive and lubrication system especially desirable. By employing the above mentioned arrangement of the under attached nut means 30 to the wedge means 40, the use of a much larger diameter adjusting bolt means 75 is now possible since the bolt means may be of a diameter even greater than the overall height of the wedge means. This provides greater load bearing capabilities. Because of the reinforcing interengagement of the nut means and the wedge means by way of the close fitting nut key 45 within the wedge groove 42, little or no impact with regard to loss of rigidity of the wedge member will be caused by the invasion of the small diameter mounting holes 43 into the wedge member. This provides improved crown rigidity and consistency. By employing the above mentioned arrangement of the under attached nut means 30 to the wedge means 40, the indicator pin 25 has no effect on the rigidity of the wedge member. This also provides improved crown rigidity and consistency. Also, by employing the above mentioned arrangement of the under attached nut means 30 to the wedge means 40, the position of the adjusting bolt means is in a convenient, unrestrictive and easily accessible centrally located position providing an extra measure of simplicity and convenience for the press operator. Importantly, this arrangement also allows for a self contained, filtering and recirculating oil lubrication system which will not contaminate or degrade the accuracy and repeatability of the wedge assemblies operation within the assembled single point compensating die holder unit as will be described in greater detail hereinafter.

[0061] It is of the greatest importance that the lubrication used to promote long life and ease of operation of the bolt and nut means does not come in contact with the interengaging mating surfaces of the base block member at surface 12 and the wedge member at surface 44, and it is especially important that this lubrication does not come into contact with the interengaging mating surfaces of the wedge member at surface 41 and the die holder member at surface 54. These interengaging surfaces of the wedge means, as will be described in greater detail hereinafter, are substantially unsupported in the longitudinally oriented areas between the ends and the center of the single point compensating die holder assembly, and therefore the application of lubrication in these areas could cause unwanted movement or sliding during load operation causing inconsistent and unreliable crown geometry's over the longitudinal length of the die holder assembly. Therefore the ability to contain the lubricating oil in oil reservoir 22 which is protected, underlocated and confined such as described above, is of great importance to the quality and performance of the single point compensating die holder assembly. Although the rotatable adjusting bolt means 75 will be completely wetted by lubricating oil, it is not anticipated that it will ever rotate at a rate high enough to cause lubricating oil to splash around or out of the oil reservoir 22, therefore insuring that the mating wedge surfaces will remain dry and oil free.

[0062] The above description of the adjusting, measuring and lubricating means used to translate the rotational adjustment of the adjusting bolt means 75 into vertical adjustment of the die holder means 50 has to this point concentrated on the longitudinal center of the compensating die holder assembly. In the following description the method by which the above adjustments are made to produce a crowning effect over the longitudinal length of the die holder assembly will be more clearly explained.

[0063]FIGS. 10 and 11 are end and foreshortened top elevations, respectively, of the single point compensating die holder assembly shown in FIG. 1, with the die and die holder removed, to illustrate the assembled adjustable wedge means. In FIG. 10 pin 80 can be clearly seen. Pin 80 is forcibly inserted into the base block 10 which is provided with a bore 81 having a diameter of a lesser size than the diameter of the pin 80 providing a press fit interengagement of the pin 80 and the base block 10. The adjoining bore 82 within the wedge means 40 however, is of a diameter greater than the diameter of the pin 80, providing a slip fit interengagement with the pin 80 and therefore allowing rotational movement around the fixed pin 80. Also noticeable in FIG. 10 of the preferred embodiment is the pinned location of the wedge means 40 within the base block 10. The wedge means being shown in a position which is closer to the rear arm portion 17 of the base block 10 than it is to the front arm portion 18. This uneven transverse spacing of the wedge means within the channel of the base block is provided because in most cases there is a greater need for positive crowning (raising the longitudinal center of the die holder) than there is for negative crowning (lowering the longitudinal center of the die holder). While such description regarding the position of the wedge means illustrates a typical arrangement, it is by no means limitive of the invention in that any desired position of the wedge within the channel and thereby any combination of positive or negative crowning limitations may be selected as desired.

[0064] As can be seen in FIG. 11 two pins 80 are provided to secure both ends of the wedge means 40 to the base block 10, one pin being located at each end and equally spaced from the center of the base block and the adjusting bolt 75 which is also located in the longitudinal center of the base block. As was described in the foregoing text the adjusting bolt means 75 is shown in FIG. 11 as having the indicating bolt groove 71 in the 12 o'clock position while the indicating pin means 25 has it's neutral face 60 flush or in smooth alignment with the front face 24 of the base block 10. In this neutral position the wedge means 40 is in parallel longitudinal alignment with the base block 10 providing zero crown over the entire length of the compensating die holder assembly. FIG. 12 is a reduced scale of the top elevation as seen in FIG. 11, showing the wedge, nut and indicating pin in a neutral operating, or zero crown position. It should be clear in this view that the wedge means 40 is in parallel longitudinal alignment with the base block 10.

[0065]FIGS. 13, 14 and 15 are end elevations of the assembly shown in FIG. 1 and sectioned transversely through the indicating pin 25, showing the cooperating nut, wedge and indicator pin means adjusted in the negative, neutral and positive crown positions, respectively. In FIG. 13 with the end of the indicator pin 25 withdrawn into the front face of the base block and having the outermost end of the indicator pin in flush and smooth alignment with the front face 24, the negative crown or height reduced at the longitudinal center of the die holder will be equal to minus 0.040″, or 0.040″ lower than the overall height at both of the ends of the compensating die holder. In FIG. 14 with the neutral face 60 of the indicator pin 25 in flush and smooth alignment with the front face 24 of the base block, the crown or height at the longitudinal center of the die holder will be equal to 0.000″, or parallel in overall height longitudinally over the entire length of the compensating die holder. In FIG. 15 with the end of the indicator pin 25 extending outwardly of the front face of the base block and having the innermost groove 65 of the indicator pin in flush and smooth alignment with the front face 24, the positive crown or height increased at the longitudinal center of the die holder will be equal to plus 0.080″, or 0.080″ higher than the overall height at both of the ends of the compensating die holder. A dashed line 89 is provided showing the relative re-positioning of the forming tool height based on the zero crown position as seen in FIG. 14.

[0066]FIG. 16 is illustrative of a typical press brake shown under forming pressure, with three separate forming tool sets of a matched height configuration installed in a normal fashion. The center tool set of this illustration being shown with material 95 being formed between the punch 93 and the die 94 and the press under a typical state of deflection as a result of the forming pressure exerted by the press brake on the material 95. Deflection of the press bed 90 and the press ram 91 is apparent as the unsupported center of the press brake bends away from the centered load exerted by the forming tools in this example as the forming tools press against the material 95 being formed. This example is typical of the deflection problem which would be expected to occur during any centered load or forming stress which is located in the longitudinal center of a typical press brake. The amount of deflection realized in the press brake will occur to a varying degree depending on the rigidity of the machine and the tonnage exerted on the machine during forming. For the purpose of this example, the deflection of the press brake shown in FIG. 16 is shown as being exaggerated. This deflection however, will cause parts to be formed with an uneven or irregular bend angle making them generally unacceptable. In a typical forming operation multiple shims of varying lengths would be stacked in such a configuration so as to produce a gently curved or crowned stack of shims which would then be placed between the die 94 and the die holder 96 so as to generate a crown equal to the amount of deflection realized in the press bed 90 and the press ram 91. At that time when the proper amount of shim is determined and placed between the die 94 and the die holder 96 good quality straight bends will be produced.

[0067]FIG. 17 is a reduced scale of the top elevation of the single point compensating die holder with the die and die holder removed, to illustrate the assembled adjustable wedge means as seen in FIG. 12, while showing the wedge, nut and indicating pin in a positive crown operating position, as would be necessary to produce good quality bends in the illustrated press brake seen in FIG. 16. It should be clear in this view that the wedge means 40 is in non-parallel or bowed longitudinal alignment with the base block 10, having the longitudinal center of the wedge in closer proximity to the front of the base block 10 at the longitudinal center of the base block. This position of the wedge at the longitudinal center is the same as is illustrated in FIG. 15, thereby providing positive crown or the raising of the center of the die holder. It is also clear in this view how the combination of the two stationary pins 80 and the pivotal engagement of the wedge 40 to the pins 80 in combination with the movement of the longitudinal center of the wedge assembly by means of the adjusting bolt 75 are used to create the desired crown under the die holder means.

[0068]FIG. 18 is illustrative of a typical press brake shown as under forming pressure, with three separate forming tool sets of a matched height configuration installed in a normal fashion. The tool set shown located at the right side of the center of the press brake in this illustration being shown with material 97 being formed between the punch 98 and the die 99 and the press under a typical state of angular deflection as a result of the off-center forming pressure exerted by the press brake on the material 97 which is on one side only of the press brake. Typical deflection of the press bed 90 and the press ram 91 as seen in FIG. 16 is minimized as the load exerted on the press brake as illustrated in FIG. 18, is now closer to the point of force 100 and the stationary point of bed support 101. This example is typical of the angular deflection problem which would be expected to occur during any off-centered load or forming stress which is located on either side of the longitudinal center of a typical press brake. The amount of angular deflection realized in the press brake will occur to a varying degree depending on the rigidity of the machine and the tonnage exerted on the machine during forming. For the purpose of this example, the deflection of the press brake shown in FIG. 18 is shown as being exaggerated. This angular deflection however, will cause parts to be formed with an uneven or irregular bend angle making them generally unacceptable. In a typical forming operation multiple shims of varying lengths would be stacked in such a configuration so as to produce a gently angled or wedge-like stack of shims which would then be placed between the die 99 and the die holder 96 so as to generate an angle equal to the amount of angular deflection realized in the press bed 90 and the press ram 91. At that time when the proper amount of shim is determined and placed between the die 99 and the die holder 96 good quality straight bends will be produced.

[0069]FIG. 19 shows in reduced scale the top elevation of the single point compensating die holder with the die and die holder removed, to illustrate the assembled adjustable wedge means as seen in FIGS. 12 and 17, while showing the wedge, nut and indicating pin in a negative crown operating position, as would be necessary to produce good quality bends in the illustrated press brake seen in FIG. 18. It should be clear in this view that the wedge means 40 is in non-parallel or bowed longitudinal alignment with the base block 10, having the longitudinal center of the wedge in closer proximity to the rear of the base block 10 than at the longitudinal center of the base block. This position of the wedge at the longitudinal center is the same as is illustrated in FIG. 13, thereby providing negative crown or the lowering of the center of the die holder. It is also clear in this view how the combination of the two stationary pins 80 and the pivotal engagement of the wedge 40 to the pins 80, in combination with the movement of the longitudinal center of the wedge assembly by means of the adjusting bolt 75, are used to create the desired negative crown under the die holder means.

[0070] It should be clearly understood from the illustrations shown in FIGS. 17 and 19 how both positive and negative crowns are produced by the use of this invention. It should also be clear how important it is to develop an even bow in the wedge means 40 so as to provide an evenly formed concentric crown over the entire length of the die holder means 50. Once the importance of an evenly developed bowing in the wedge means 40, as seen in FIGS. 17 and 19, is fully understood, the significant advantages associated with the under mounted nut means 30 can be fully appreciated. The increased rigidity offered by the engagement of the nut means key 45 into the full length wedge means keyway 42 is provided so as to offset the low impact weakening of the wedge means by the nut means mounting screws which engage the small diameter threaded holes 43 in the wedge means. By eliminating weakening of the wedge means, by the use of large through holes, slots or machined pockets as seen in the prior art, which can cause kinking rather than uniform bowing of the wedge means and binding on the adjusting screw means, even bowing and the smooth operation of the wedge is assured and improved part quality is provided.

[0071]FIGS. 20 and 21 are foreshortened top and front elevations, respectively, of the center portion of the single point compensating die holder showing the optional addition of a power drive unit 110 used to operate in cooperation with the adjusting screw 75 and nut assembly to provide an automatic interface and cooperation of the press brake and the single point compensating die holder. In FIG. 20 the optional power drive unit 110 containing the drive motor and encoder unit can be seen mounted to the front face 24 of the base block 10 of the single point compensating die holder. The encoder unit enclosed within the drive unit 110 provides communication input to the press brake control computer so as to convey the exact position of the wedge assembly within the base block by electrical output means supplied to the press computer by way of the power and control wire 111 shown. Visual reference for the operator is still provided by way of the indicating pin 25 as has been fully explained in the foregoing. FIG. 21 shows the relative mounting location of the optional power drive unit as seen from the front of the die holder. The ability to use a press computer controlled adjustment system has great value in those applications where multiple forming tools are used in the press brake at the same time and therefore adjustment of the die holder is desirable between each stroke of the press as the part being produced is cycled from one forming tool to the next. It is during these applications that the lubrication system described in the foregoing is of particular benefit so as to insure a long dependable service life for the single point compensating die holder.

[0072] From the foregoing it is believed that those familiar with the art will readily recognize the novel advancement presented by this invention over prior compensating die holders and will readily appreciate that while the same has been described in conjunction with a particular preferred embodiment thereof illustrated in the accompanying drawings, the same is susceptible to variation, modification and substitution of equivalents without departing from the spirit and scope of the invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. 

That which is claimed is:
 1. A compensating die holder for use with a press brake, comprising: a base block having an elongated rigid body of a substantially U-shaped cross-section formed with an elongated channel opening inwardly of one face thereof, said channel being disposed between parallel arm portions of said body, and including means for attachment of said base block to a bed of the press; an elongated die holder mounted in said channel for limited vertical movement guided by opposing walls of said arm portions; wedge means mounted between the bottom of said channel and said die holder so as to allow limited transverse movement of said wedge means in said channel, said transverse movement of said wedge means effecting vertical movement of said die holder; means for securing opposing end portions of said wedge means to respective end portions of said base block to restrict transverse movement of said end portions of said wedge means with respect to said base block; a recess provided in the bottom of said channel; a connection means provided in said recess and connected to said wedge means; and an adjustment means extending transversely through said body and said recess, and connected to said connection means, whereby said wedge means is adjustably moved transversely in said channel in response to movement of said adjustment means to effect vertical movement of said die holder.
 2. The compensating die holder of claim 1 wherein a keyway is provided in an underside surface of said wedge means and. an insert key is provided on said connection means which engages said keyway for connecting said wedge to said connection means.
 3. The compensating die holder of claim 1 wherein said connection means is closely fit between an underside of said wedge means and a bottom surface of said recess.
 4. The compensating die holder of claim 2 wherein said connection means is further connected to said wedge means by at least one connecting bolt.
 5. The compensating die holder of claim 2 wherein said keyway extends to both longitudinal ends of said wedge means.
 6. The compensating die holder of claim 1 wherein said adjustment means is a bolt means having threading engagement with said connection means whereby said wedge means is adjustably moved transversely in said channel in response to rotation of said bolt means.
 7. The compensating die holder of claim 6 wherein said bolt means and said connection means are removable and replacable components of said die holder.
 8. The compensating die holder of claim 1 wherein said adjustment means is a hydraulic actuator.
 9. The compensating die holder of claim 1 further comprising an indicator means, independent from said adjustment means, which is responsive to movement of said wedge means and operable to visually indicate the transverse position of said wedge means in said channel.
 10. The compensating die holder of claim 9 wherein said indicator means comprises an elongated pin means separate from said adjustment means and connected and movable with said wedge means; said pin means extending through at least one of said arm portions so as to visibly protrude from the exterior of said base block.
 11. The compensating die holder of claim 10 wherein said elongated pin means is attached to said connection means.
 12. The compensating die holder of claim 6 further comprising: an elongated pin means separate from said adjustment means and connected and movable with said wedge means; said pin means extending through at least one of said arm portions so as to visably protrude from the exterior of said base block; said pin means including a linear scale means for measuring the linear displacement of said wedge means; said bolt means including a rotational scale means for measuring the linear displacement of said wedge means in relation to the rotation of said bolt means.
 13. The compensating die holder of claim 12 wherein said elongated pin means is attached to said connection means.
 14. The compensating die holder of claim 12 wherein said rotational scale means includes ten rotational increments, each of said ten rotational increments measuring one-thousandth of an inch of vertical displacement of the die holder; and said linear scale means includes linear increments which measure one-hundredth of an inch of vertical displacement of the die holder.
 15. The compensating die holder of claim 1 wherein said adjustment means displaces said wedge means forward and rearward transversely in said channel to provide both positive and negative crowning of said die holder.
 16. The compensating die holder of claim 1 further comprising retainment means for retaining said die holder on said bolster block when a force is applied on said die holder away from said base block.
 17. The compensating die holder of claim 16 wherein said retainment means comprises retaining bolts extending through said die holder and engaging with said base block, and allowing said limited vertical movement of said die holder.
 18. The compensating die holder of claim 1 wherein a lubricant is provided in said recess.
 19. The compensating die holder of claim 6 wherein a lubricant is provided in said recess.
 20. The compensating die holder of claim 19 wherein a groove is provided in said connecting means to expose said bolt means to the lubricant.
 21. The compensating die holder of claim 20 wherein said lubricant is a lubricating oil and a wicking material is provided within said groove to allow said lubricating oil to be transported through said wicking material onto said bolt means.
 22. The compensating die holder of claim 21 wherein said wicking material further functions to filter said lubricating oil.
 23. The compensating die holder of claim 1 further comprising a power drive unit for actuating said adjustment means.
 24. The compensating die holder of claim 23 wherein said power drive unit is controlled by a control computer capable of receiving and displaying input regarding the transverse position of the wedge means in said channel.
 25. The compensating die holder of claim 23 wherein said adjustment means is a bolt means having threading engagement with said connection means whereby said wedge means is adjustably moved transversely in said channel in response to rotation of said bolt means; and further comprising: an elongated pin means separate from said adjustment means and connected and movable with said wedge means; said pin means extending through at least one of said arm portions so as to visably protrude from the exterior of said base block; said pin means including a linear scale means for measuring the linear displacement of said wedge means; said bolt means including a rotational scale means for measuring the linear displacement of said wedge means in relation to the rotation of said bolt means.
 26. The compensating die holder of claim 24 wherein said control computer automatically adjusts the transverse position of the wedge means in said channel in response to programming input by an operator. 